1. Field of the Invention
The present invention relates to an ionic compound, and a radiation polymerization initiator comprising the compound, a resin composition containing the initiator and the use thereof.
2. Description of the Related Art
An onium salt or an organometallic complex salt is known as a photocationic polymerization initiator of a monomer and/or a polymer containing a functional group such as epoxy, vinyl ether, and oxetane. It has been confirmed that these salts exhibit an excellent hardening ability when an anion of an initiator salt is SbF6−. However, there is a risk of toxicity from the initiator salt containing this type of anion. Patent Document 1 discloses that tetrakis(pentafluorophenyl)borate, which is an anion having nucleophilicity similar to that of SbF6−, is used in a new onium borate or borate of an organometallic complex used as the photocationic polymerization initiator. Patent Document 2 discloses a new aromatic sulfonium compound, a photo-acid generator comprising the compound and a photopolymerizable composition containing the generator. However, there are problems in regards to the environment and pollution to peripheral members caused by outgas generated from the onium salt, the onium salt being used as a countercation during polymerization or crosslinking reactions by a photochemical means or under electron beam irradiation.
[Patent Document 1] Japanese Patent No. 2557782
[Patent Document 2] Japanese Patent Laid-Open No. 2000-186071